Full Adder

 

Home NOT Gate AND Gate OR Gate XOR Gate Half-Adder Full Adder SR Flip Flop

The full-adder circuit adds three one-bit binary numbers (C A B) and outputs two one-bit binary numbers, a sum (S) and a carry (C1).   The full-adder is usually a component in a cascade of adders, which add 8, 16, 32, etc. binary numbers.  The carry input for the full-adder circuit is from the carry output from the circuit "above" itself in the cascade.  The carry output from the full adder is fed to another full adder "below" itself in the cascade.

If you look closely, you'll see the full adder is simply two half adders joined by an OR.

Select an input combination from the pull-down selector and view the resulting output.

Full Adder Circuit Truth Table
Input Output
C A B S C
0 0 0 0 0
1 0 0 1 0
0 1 0 1 0
1 1 0 0 1
0 0 1 1 0
1 0 1 0 1
0 1 1 0 1
1 1 1 1 1
Select An Input Value